Do 17Z-2 Specifications
Crew: Pilot and four gunners/navigators/bomb-aimers
Powerplant: Two 1,000 hp Bramo 323P nine-cylinder air-cooled engines
Span: 59 ft ¾ in (18.00 m)
Length: 52 ft 0 in (15.85 m)
Max Speed: 265 mph (427 km/h) at 16,400 ft (4,998 m)
Armament: Between four and eight 7.92 mm machine guns in front, rear and beam cockpit mountings and ventral position
Bomb Load: Normal load of 2,200 lb (1,000 kg)
Image: A Dornier Do 17Z bomber of KG 76 in flight, 1940. Bundesarchiv, Bild 101I-341-0489-10A / Spieth / CC-BY-SA 3.0
The Dornier Do 17 was a German twin-engine light bomber used by the Luftwaffe during the early campaigns of the Second World War, including the Battle of Britain. Initially conceived in the early 1930s as a fast mail and passenger aircraft for Deutsche Lufthansa, the aircraft was developed by Dornier Flugzeugwerke under the designation Do 17. Three prototypes were constructed, but the design was rejected by Lufthansa due to its slim fuselage, which limited passenger capacity and cargo space, making it commercially unviable.
One of the prototypes was later test-flown by Flugkapitän Robert Untucht, a Lufthansa test pilot closely associated with Dornier. Recognizing its potential, he advocated for the design to fulfill the Luftwaffe’s Schnellbomber (“fast bomber”) requirement—an aircraft intended to be so fast it could evade interception by enemy fighters. The Luftwaffe accepted the idea, and Dornier modified the design to include a glazed nose section, internal bomb bay, twin rudders, and defensive armament. The fuselage’s narrow, elongated profile earned it the nickname “Fliegender Bleistift” (“flying pencil”).
The militarized prototypes first flew in 1935 and demonstrated impressive speed, outpacing many contemporary fighters. Two versions entered production shortly thereafter: the Do 17E-1 light bomber and the Do 17F-1 reconnaissance model, both powered by two BMW VI 7.3 V-12 engines producing 750 hp each. The E-1 could carry a 750 kg (1,654 lb) bomb load and reached a top speed of 380 km/h (236 mph). Defensive armament consisted of two 7.92 mm MG 15 machine guns – one dorsal and one ventral. These early variants entered Luftwaffe service in early 1937 and first saw combat during the Spanish Civil War with the Condor Legion, where they performed well under relatively uncontested conditions.
With production ramping up, Dornier continued developing more powerful variants. In July 1937, the Do 17M V-1 prototype, fitted with two 1,000 hp Daimler-Benz DB 600A engines, was entered into the International Military Aircraft Competition in Zürich. It impressed observers by reaching 457 km/h (284 mph), faster than all participating fighter aircraft. However, limited availability of DB 600 series engines prevented mass production of the M variant. Instead, development shifted to radial-powered versions, with the production Do 17M-1 fitted with Bramo Fafnir 323 A radial engines. This reduced top speed to 420 km/h (261 mph) but increased bomb load capacity to 1,000 kg (2,204 lb) and added a fourth crew member. An additional fixed forward-firing MG 15 was mounted in the windscreen.
The Do 17P-1, a long-range reconnaissance variant, featured BMW 132N engines for extended range. However, combat experience in Spain revealed that the Do 17’s speed advantage had diminished. New Soviet-supplied Republican fighters were able to intercept it, prompting a redesign of the forward fuselage to improve visibility, crew space, and defensive armament. These changes were introduced with the Do 17S and Do 17U pathfinder versions, both powered by DB 600 engines. However, only limited numbers were built.
The definitive production version was the Do 17Z, introduced in 1938. It featured the redesigned forward fuselage and Bramo 323 radial engines. The initial Z-1 variant could carry only a 500 kg (1,102 lb) bomb load and was underpowered. This was addressed with the Z-2, introduced in 1939, which featured Bramo 323 P engines with two-speed superchargers and an improved payload capacity of 1,000 kg (2,204 lb). Defensive armament was typically increased to six MG 15s mounted in the nose, dorsal, ventral, and side positions. Some aircraft were later fitted with additional guns in field modifications. Nevertheless, the aircraft’s combat radius—around 500–600 km (310–370 mi) under operational conditions—remained a significant limitation. Production of the Do 17 ceased in mid-1940, as Luftwaffe units transitioned to the faster and more versatile Junkers Ju 88.
At the start of the Battle of Britain, three Kampfgruppen still operated the Do 17. Its agile handling at low altitude and the durability of its air-cooled engines made it well-suited for low-level precision strikes. On 18 August 1940—known as the “Hardest Day”—nine Do 17s of 9./KG 76 launched a daring low-level attack on RAF Kenley, destroying hangars, buildings, and several aircraft on the ground. However, four bombers were shot down, two were severely damaged, and the remainder suffered varying degrees of damage. Despite improved defensive firepower, the Do 17 remained highly vulnerable to RAF fighters.
On 15 September 1940, during Battle of Britain Day, twenty Do 17s were destroyed and thirteen damaged. Among them was Do 17Z-2 Wk-Nr 2361 ‘F1+FH’ of 1./KG 76, famously brought down over London by Sergeant Ray Holmes of No. 504 Squadron RAF, who rammed the bomber after his guns jammed. The Do 17 crashed near Victoria Station, while Holmes bailed out and survived—his damaged Hurricane coming down near Buckingham Palace.
The Dornier Do 215, a development of the Do 17, was externally similar but powered by Daimler-Benz DB 601 inline engines. Originally intended for export to Yugoslavia and Sweden, the type was taken over by the Luftwaffe after the outbreak of war. The Do 215 saw limited use during the Battle of Britain, primarily in the reconnaissance role.